Slime control compositions and their use

ABSTRACT

The present invention relates to certain processes and compositions useful for inhibiting the growth of slime in water and, in particular, water used for industrial purposes; for example, in the manufacture of pulp paper, in the manufacture of paper, in cooling water systems and in effluent water treatment. The novel processes and compositions of the present invention are processes or mixtures which show unexpected synergistic activity against microorganisms, including bacteria, fungi, and algae, which produce slime in aqueous systems or bodies which are objectionable from either an operational or aesthetic point of view. Specifically, the invention is directed to the use of compositions comprising a combination of a mixture of 75% of 5chloro-2-methyl-4-isothiazolin-3-one calcium chloride and 25% 2methyl-4-isothiazolin-3-one calcium chloride and octyl-phenoxy polyethoxy ethanol.

United States Patent Shema et al.

[ 1 July 22,1975

[ SLIME CONTROL COMPOSITIONS AND THEIR USE [73] Assignee: Betz Laboratories, Inc., Trevose, Pa.

[22] Filed: I Aug. 27, 1973 [21] Appl. No.: 391,724

[52] US. Cl. 424/270; 71/67; 162/161;

424/341 [51] Int. C13... A01N 9/12;A01N 9/20;AO1N 9/24 [58] Field of Search 424/270, 341; 71/67 [56] References Cited OTHER PUBLICATIONS Chemical Abstracts 51:6066H (1957). Chemical Abstracts 61:167l5a (1964). Chemical Abstracts 721-111459n (1970). Chemical Abstracts 72:55438n (1970). Chemical Abstracts 75:1102l9j (1971).

Primary Examiner-Albert T. Meyers Assistant Examiner-Leonard Schenkman Attorney, Agent, or Firm-Alexander D. Ricci 57 ABSTRACT The present invention relates to certain processes and compositions useful for inhibiting the growth of slime in water and, in particular, water used for industrial purposes; for example, in the manufacture of pulp paper, in the manufacture of paper, in cooling water systems and in effluent water treatment. The novel processes and compositions of the present invention are processes or mixtures which show unexpected synergistic activity against microorganisms, including bacteria, fungi, and algae, which produce slime in aqueous systems or bodies which are objectionable from either an operational or aesthetic point of view. Specifically, the invention is directed to the use of compositions comprising a combination of a mixture of 75% of 5-chloro-2-methyl-4isothiazolin-3-one calcium chloride and 25% Z-methyl-4-isothiazolin-3- one calcium chloride and octyl-phenoxy polyethoxy ethanol.

8 Claims, No Drawings SLIME CONTROL COMPOSITIONS AND THEIR USE BACKGROUND OF THE INVENTION The formation of slime by microorganisms is a problem which attends many systems. For example, lagoons, lakes, ponds, pools, and such systems as cooling water systems and pulp and paper mill systems all possess conditions which are conducive to the growth and reproduction of slimcforming microorganisms. In both once-through and recirculating cooling systems, for example, which employ large quantities of water as a cooling medium, the formation of slime by microorganisms is an extensive and constant problem.

Airborne organisms are readily entrained in the water from cooling towers and find this warm medium an ideal environment for growth and multiplication. Aerobic and heliotropic organisms flourish on the tower proper while other organisms colonize and grow in such areas as the tower sump and the piping and passages of the cooling system. Such slime serves to deteri' orate the tower structure in the case of wooden towers. In addition, the deposition of slime on metal surfaces promotes corrosion. Furthermore. slime carried through the cooling system plugs and fouls lines, valves, strainers, etc. and deposits on heat exchange surfaces. In the latter case, the impedance of heat transfer can greatly reduce the efficiency of the cooling system.

In pulp and paper mill systems, slime formed by microorganisms is also frequently and, in fact, commonly encountered. Fouling or plugging by slime also occurs in the case of pulp and paper mill systems. Of greater significance, the slime becomes entrained in the paper produced to cause breakouts on the paper machines with consequent work stoppages and the loss of production time or unsightly blemishes in the final product which results in rejects and wasted output. The previously discussed problems have resulted in the extensive utilization of biocides in cooling water and pulp and paper mill systems. Materials which have enjoyed widespread use in such applications include chlorine, organomercurials, chlorinated phenols, organobromines, and various organo-sulfur compounds. All of these compounds are generally useful for this purpose but each is attended by a variety of impediments. For example, chlorination is limited both by its specific toxicity for slime-forming organisms at economic levels and by the ability of chlorine to react which results in the expenditure of the chlorine before its full biocidal function may be achieved. Other biocides are attended by odor problems and hazards in respect to storage, use or handling which limit their utility. To date, no one compound or type of compound has achieved a clearly established predominance in respect to the applications discussed. Likewise, lagoons, ponds, lakes and even pools, either used for pleasure purposes or used for industrial purposes for the disposal and storage of industrial wastes, become, during the warm weather, besieged by slime due to microorganism growth and reproduction. In the case of the recreational areas, the problem of infection, etc. is obvious. In the case of industrial storage or disposal of industrial materials, the microorganisms cause additional problems which must be eliminated prior to the materials use or the waste is treated for disposal.

Naturally, economy is a major consideration in respect to all of these biocides. Such economic considerations attach to both the cost of the biocide and the expense of its application. The cost performance index of any biocide is derived from the basic cost of the material, its effectiveness per unit of weight, the duration of its biocidal or biostatic effect in the system treated, and the ease and frequency of its addition to the system treated. To date, none of the commercially available biocides have exhibited a prolonged biocidal effect. Instead, their effectiveness is rapidly reduced as the result of exposure to physical conditions such as temperature, association with ingredients contained by the system toward which they exhibit an affinity or substantivity, etc., with a resultant restriction or elimination of their biocidal effectiveness.

As a consequence, the use of such biocides involves their continuous or frequent addition to systems to be treated and their addition to a plurality of points or zones in the systems to be treated. Accordingly, the cost of the biocide and the labor cost of such means of applying it are considerable. In other instances, the difficulty of accessto the zone in which slime formation is experienced precludes the effective use of a biocide. For example, ina particular system there is no access to an area at which slime formation occurs and it may only be applied at a point which is upstream in the flow system. However, the physical or chemical conditions, e.g., chemical reactivity, thermal degradation, etc. which exist between the point at which the biocide may be added to the system and the point at which its biocidal effect is desired render the effective use of a biocide impossible,

Similarly, in a system experiencing relatively slow flow, such as a paper mill, if a biocide is added at the beginning of the system, its biocidal effect may be completely dissipated before it has reached all of the points at which this effect is desired or required. As a consequence, the biocide must be added at a plurality of points, and even then a graduated biocidal effect will be experienced between one point of addition to the system and the next point downstream at which the biocides may be added. In addition to the increased cost of utilizing and maintaining plural feed points, gross ineconomies in respect to the cost of the biocide are experienced. Specifically, at each point of addition, an excess of the biocide is added to the system in order to compensate for that portion of the biocide which will be expended in reacting with other constituents present in the system or experience physical changes which impair its biocidal activity.

It is an object'of the present invention to provide methods and compositions for controlling slimeforming microorganisms in aqueous systems such as cooling water systems and pulp and paper mill systems, and for controlling slime formation or microorganism populations in aqueous bodies in general. Moreover, another object of the invention is the provision of methods and compositions for controlling slimeforrning microorganisms in any aqueous system which is conducive to the growth and reproduction of microorganisms and, in particular, cooling water and paper and pulp mill systems which employ a combination of a mixture of of 5-chloro-2-methyl-4-isothiazolin- 3-one calcium chloride and 25% 2-methyl-4- isothiazolin-3-one calcium chloride and octyl-phenoxy polycthoxy ethanol.

, In practice of the invention, the combination is added to the particular system being treated; for example,

cooing water systems, paper and pulp mill systems, pools, ponds, lagoons, lakes, etc. in a quantity adequate to control the slime-forming microorganisms which are OLOGY, 9, 538-41, (1946), and the relationships,

contained by, or which may become entrained in, the system which is treated. It has been found that such 5 compositions and methods control the growth and i is y i is antagonism and i is currence of such microorganisms as may populate additivity where. these particular systems. Q Quantity of Compound A. acting alone, produc- A mixture of 75% of -chloro-2-mcthyl-4- ing an end point isothiazolin-S-one calcium chloride and 25% l0 Q Quantity f Compound B- a ting alone. produc- 2-methyl-4-isothiazolin-3-one calcium chloride is availing an end point able commercially as Rohm & Haas RH-886 and octyl- Q, Quantity of Compound A, in the mixture, prophenoxy polyethoxy ethanol is available as Rohm & duciiig an end point Haas Triton X-l 14 where this ethanol possesses an av- OR Quantity of Compound B, in the mixture, pro erage molecular weight of about 536 and has a Brook- 15 dilcing end point field viscosity (12 rpm) at 25C of about 260 cps. For mixtures of Compounds A and B, and for Com- As earlier stated, the inventive compositions are pound A and Compound B acting alone, the following comprised of the latter compounds, either compound results were observed. being present in such a quantity as to impart a synergis- Summary of synergistic activity of varying percenttic behavior to the composition as a whole, the weight ages of Compound A and Compound B: ratio of the Rohm & Haas RH-886 to the Rohm & Haas Triton X-l l4 ranging from about 95:5 to about 5:95. SYNERGISTIC COMBINATlON When these two ingredients are mixed, the resulting Compound A; a mixture of 75% of 5-chloro-2- mixtures possess a high degree of slimicidal activity methyl-4-i$0thiaZO]in-3-On calcium chloride and which could not have been predicted beforehand from 25% 2-methyl-4-isothiazolin 3-one calcium chlothe known activity of the individual ingredients comride (RH-886) prising the mixture. Accordingly, it is therefore possi- Compound B: octyl-phenoxy polyethoxy ethanol ble to produce a more effective slime-control agent (Triton X-l l4) TABLE 1 TEST ORGANISM AEROBACTER AEROGENES Quantities Produc- Q Q Q Weight ratio ing End Points (ppm) A B A B of A to B Q Q Mixture Q Q Q Q A B Mixture a h a b than has previously been available. Because of the en- The mode of establishing the synergistic behavior of hanced activity of the mixture, the total quantity of the the compositions of the present invention is a widely biocide required for an effective treatment may be reused and an industirally acceptable procedure. Alduced. In addition, biocide required for an effective though it is believed that the above is sufficient in extreatment may be reduced. In addition, the high degree plaining he procedure. for a further description of biocidal effectiveness which is provided by each of thereof reference can be made to U.S. Pat. No. the ingredients may be exploited without use of the 3,231,509 and its file history where data of this nature higher concentrations of each. was considered to be acceptable. Moreover, the article To demonstrate the synergism which is provided b by Kull et al published in APPLIED MICROBIOL- the inventive combinations of compounds, the data as 9, 5 ill furnish additional information set forth in the Table below was developed. in this regard.

For the testing to ascertain synergistic behavior, Aer- EXAMPLE 1 is obac'ter aerogenes was favored since this microorganism Synergism was demonstrated by adding Compound A is found to exist and found to be most troublesome in and Compound B in varying ratios and over a range of pulp and paper producing processes. as well as in coolconcentrations to liquid nutrient agar medium (Tryping towers. Moreover. this microorganism is difficult to tone Glucose Extract Agar) at approximately 50 C. control and/or kill and accordingly its existence does After the medium had solidified in Petri plates, it was give rise to troublesome slime. In view of the foregoing, inoculated with a bacterial suspension. Following two it can then be appreciated that since Aerubacler aerodays incubation, the lowest concentration of each ratio genes is prevalent in most slime-affected systems and which prevented growth on the agar medium was taken since this microorganism is difficult to control or kill, as the end point. End points for the various mixtures that once control of this microorganism is maintained, were then compared with end points for the pure active then for all practical purposes the total microorganism ingredients working alone in concomitantly prepared agar medium plates. Synergism was determined by the method described by F. C. Kull. P. C. Eisman, H. D. Sylwestrowicz and R. L. Mayer. APPLIED MICROBI- population with its different types is considered controlled.

When the inventive compositions are employed in the treatment of cooling or paper mill water, they are preferably utilized in the form of relatively dilute solutions or dispersions. For example, a preferred solution comprises betweenS to 65% by weight of the synergistic combination in admixture with various solvents and solubilizing agents.

Surfactants such as the alkylaryl polyether alcohols, polyether alcohols, alkyl benzene sulfonates and sulfates, and the like, may also be employed to enhance the dispersibility and stability of these formulations. The foregoing solutions of the biocidal compositions are utilized in order to insure the rapid and uniform dispersibility of the biocides within the industrial water which is treated. It has been found that either aqueous or non-aqueous solvents are generally suitable in the preparation of compositions of the invention. For example, organic solvents such as methyl cellosolve and aliphatic and aromatic hydrocarbons, e.g., kerosene, can be used quite successfully. Based upon the synergism study as outlined above, it was ascertained that in the treatment of paper mill and cooling water, effective biocidal action is obtained when the concentration or treatment level of the combination or admixture of biocides is between 0.5 parts per million to 1000 parts per million, and preferably between 1 and I parts per million, based upon the total content of the system treated, such as the total quantity of cooling water or paper mill water.

The compositions may also be utilized for the preservation of slurries and emulsions containing carbohydrates, proteins, fats, oils, etc. Dosage levels for this purpose range in the vicinity of 0.01 to 5%.

The compositions of the invention which can be prepared by merely combining the respective ingredients and mixing thoroughly at standard conditions may be lapse and the conditions experienced betweenpoint of addition and the point at which the effect of the composition is experienced are not so drastic as to result in the neutralization of the effect of the composition.

SLIME CONTROL EFFECTIVENESS The inventive methods and materials were tested with respect to their performance in the control of slime formation in industrial systems, In this test an industrial recirculating water was obtained from a system which was currently experiencing problems in respect to the formation of slime by microorganisms. Such tests do not demonstrate the efficiency of the biocide employed with respect to specific species of microorganisms but instead supply a practical demonstration of the efficacy of the biocide tested in relation to those communities of microorganisms which have evidenced their ability to form slime in actual industrial systems.

In testing of recirculating water samples, a substrate evaluation was employed. In such testing, identical portions of water samples are treated with varying concentrations of biocide and two portions are left untreated to serve as controls. The control portions are plated for total count at the beginning of biocide treatment and all portions are plated for total count at some suitable time period(s) after beginning biocide treatment. Using the counts obtained from the platings, the percentage kill (based on the initial control count) may be calculated. In the following example, the water sample was taken from a fine paper mill in mid-eastern United States.

For the purposes of comparison, a composition of this invention was evaluated with two recognized commercial biocides.

fed continuously to the treated system, e.g., by means of a metered pump, or may be fed periodically at intervals calculated to control the growth of slime-forming organisms in the system. Naturally, in the treatment of cooling water the feeding of the inventive compositions must be designed to compensate for blow'down in those systems which employ that expedient.

As would be expected, the inventive composition may be added to the cooling water or paper and pulp mill systems at any convenient point. Naturally, in once-through or non-circulating systems, the composition must be added upstream fromthe point or points at which microorganism control is desired. In circulat ing systems or pulp and paper systems, the compositions may be added at any point provided that the time EFFICACY RELATIVE TO FUNGI In order to ascertain whether in fact the inventive compositions were effective in controlling fungi, evaluations were made following the procedure described by Shema et al, JOURNAL FOR THE TECHNICAL AS- SOCIATION OF THE PULP AND PAPER INDUS- TRY,36, 20A-30A, 1953. The described procedure generally entails incorporating the biocide under test in a nutrient substrate such as agar, malt, etc. and pouring the resulting medium in a Petri dish and allowing the medium to solidify. A button of fungus inoculum is placed on the surface of the solidified medium and the medium is incubated for a period of 14 days. After the period, the diameter of the colony is measured and compared with the diameter of the button of inoculum originally placed upon the surface. If there is no increase in the diameter, the growth of the fungus is considered to be completely inhibited and the-treatment level which effectuates this is considered the inhibitory concentration.

The fungi species utilized as the test microorganism to evaluate the efficacy of the present compositions were Penicillium expansum and Aspergillus niger. The study revealed that the above 10% active composition of this invention inhibited the growth of Penicillium expansum at a treatment level of 400 ppm and 600 ppm completely inhibited the growth of Aspergillus niger.

BACTERICIDAL EFFECTIVENESS The bactericidal effectiveness of a U1 mixture of the two components of this invention 10% Active) is demonstrated by the following data in which the inhibiting power is shown in comparison with a commercial biocide. Aerobacter aerogenes was employed as the test organism and a substrate technique was utilized. Specifically, the biocidal mixture was added in gradually increasing quantities to nutrient agar media which was then innoculated with Aerobacter aerogenes. The preparation was then incubated for 48 hours. The below values indicate the quantity of biocide required to achieve complete inhibition of the growth of the test organism. The biocide RX-38 is available commercially from Betz Laboratories, Inc. and contains as active ingredients about 23% methylene bisthiocyanate and about 77% hexachloro dimethyl sulfone.

Biocide Materials Inhibition quantity 1. Rohm & Haas RH886 (90% sol) (5%) 75 Rohm & Haas Triton X-l 14 (5'71) Inert (90%) 2. RX-38 (100%) 30 evidence has been derived from the treatment of samples taken from paper and pulp mill aqueous systems, the compositions and methods of the present invention are broadly applicable to the treatment of aesthetic waters as well as industrial waters such as cooling waters which are plagued by deposits formed by slime-forming organisms, or by the very presence of such organisms.

Having thus described the invention what is claimed 1. A composition for the control of the microorganism Aerobacter aerogenes in aqueous systems comprising a mixture of of 5-chloro-2-methyl-4- isothiazolin-3-one calcium chloride and 25% 2-methyl-4-isothiazolin-3-one calcium chloride with an octyl-phenoxy polyethoxy ethanol, said ethanol possessing an average molecular weight of about 536 and a Brookfield viscosity 12 rpm) of about 260 cps at 25 C, wherein the weight ratio of the chloride mixture of the ethanol ranges from about :5 to about 5:95 respectively.

2. The composition of claim 1 where said ratio is about 50:50.

3. A method for controlling the growth of the microorganism Aerobacter aerogenes in an aqueous system which comprises adding to said system a growth inhibiting amount of a composition comprised of a mixture of 75% of S-chloro-2-methyl-4-isothiazolin-3-one calcium chloride and 25% of the 2-methyl-4-isothiazolin-3-one calcium chloride with an octyl-phenoxy polyethoxy ethanol, said ethanol possessing an average molecular weight of about 536 and a Brookfield viscosity (12 rpm) of about 260 cps at 25 C, wherein the weight ratio of the chloride mixture to the ethanol ranges from about 95:5 to 5:95 respectively.

4. The method of claim 3 wherein said ratio is about 50:50.

5. The method of claim 3 wherein said composition is added to said system in an amount of from 0.1 to about 1000 parts per by weight of said composition per million parts by weight of said aqueous system.

6. The method of claim 5 where said composition amount is from about 1 to about parts per million of said aqueous system.

7. The method of claim 5 wherein the aqueous system is that of a cooling water system.

8. The method of claim 5 wherein the aqueous system is that of a pulp and paper mill system.

l l= l= 

1. A COMPOSITION FOR THE CONTROL OF THE MICROORGANISM AEROBACTER AEROGENES IN AQUEOUS SYSTEMS COMPRISING A MIXTURE OF 75% OF 5-CHLORO-2-METHYL-4-ISOTHIAZOLIN-3-ONE CALCIUM CHLORIDE AND 25% 2-METHYL-4-ISOTHIAZOLIN-3-ONE CALCIUM CHLORIDE WITH AN OCTYL-PHENOXY POLYETHOXY ETHANOL, SAID ETHANOL POSSESSING AN AVERAGE MOLECULAR WEIGHT OF ABOUT 536 AND A BROOKFIELD VISCOSITY (12 RPM) OF ABOUT 260 CPS AT 25*C, WHEREIN THE WEIGHT RATIO OF THE CHLORIDE MIXTURE OF THE ETHANOL RANGES FROM ABOUT 95:5 TO ABOUT 5:95 RESPECTIVELY.
 2. The composition of claim 1 where said ratio is about 50:50.
 3. A method for controlling the growth of the microorganism Aerobacter aeRogenes in an aqueous system which comprises adding to said system a growth inhibiting amount of a composition comprised of a mixture of 75% of 5-chloro-2-methyl-4-isothiazolin-3-one calcium chloride and 25% of the 2-methyl-4-isothiazolin-3-one calcium chloride with an octyl-phenoxy polyethoxy ethanol, said ethanol possessing an average molecular weight of about 536 and a Brookfield viscosity (12 rpm) of about 260 cps at 25* C, wherein the weight ratio of the chloride mixture to the ethanol ranges from about 95:5 to 5:95 respectively.
 4. The method of claim 3 wherein said ratio is about 50:50.
 5. The method of claim 3 wherein said composition is added to said system in an amount of from 0.1 to about 1000 parts per by weight of said composition per million parts by weight of said aqueous system.
 6. The method of claim 5 where said composition amount is from about 1 to about 100 parts per million of said aqueous system.
 7. The method of claim 5 wherein the aqueous system is that of a cooling water system.
 8. The method of claim 5 wherein the aqueous system is that of a pulp and paper mill system. 